Maintained-position interlocking mechanism for interlocking a pair of pushbutton switches



July 2. 1968 s. L.'FF\ANK MAINTAINED-POSITION INTERLOCKING MECHANISM FORINTERLOCKING A PAIR OF PUSHBUTTON SWITCHES Filed Feb. 14, 1967 2Sheets-Sheet 1 INVENTOR Stanley L. Frank BY M WITNESSES ATTORNEY July 2.1968 2 Sheets-Sheet 7-? S. L. FRANK MAINTAINED-POSITION INTERLOCKINGMECHANISM FOR INTERLOCKING A PAIR OF PUSHBUTTON SWITCHES Filed Feb. 14,1967 FIG. 5

FIG.4

United States Patent 3,391,257 MAlNTAlNED-PUSHTION INTERLOCKING MECH-ANISM FQR INTERLOCKING A PAIR OF PUSH- BUTTON SWITQCHES Stanley L.Frank, Beaver, Pa, assignor to Westinghouse Electric Corporation,Pittsburgh, Pa., 'a corporation of Pennsylvania Filed Feb. 14, 1967,Ser. No. 616,037 10 Claims. (Cl. 200-) ABSTRACT OF THE DISCLOSURE Amaintained-position interlocking mechanism for interlocking a pair ofpushbutton switches for operation between two maintained positions.

An improved interlocking mechanism comprises a support and an elongatedconnecting arm pivotally mounted on the support intermediate the endsthereof with means for connecting operating structures of two pushbuttonswitches to the connecting arm at opposite sides of the pivot. A pair oflink members are pivotally mounted on the support on opposite sides ofthe pivot of the connecting arm. The link members are connected to theconnecting arm at opposite sides of the pivot of the connecting arm bylost-motion connecting means. An over-center spring connects the linkmembers. When one of the pushbutton operators is depressed theinterlocking mechanism is operated over center to raise the pushbuttonoperator. The over-center spring maintains the connecting arm, andtherefore the pushbutton operators, in posilion until the otherpushbutton operator is depressed. The link of the lever arm of each linkmember between the pivotal support thereof and the position Where thelink member is connected to the connecting arm can be adjusted so thatthe interlocking mechanism can be used with push buttons havingdifferent dimensions of operator travel.

An object of this invention is to provide an improvedmaintained-position interlocking mechanism for interlocking a pair ofpushbutton switches for seesaw type operation between two maintainedpositions.

Another object of this invention is to provide an improvedmaintained-position interlocking mechanism that is adapted so that themechanism can be adjusted to be used with pushbuttons having differentdimensions of operator travel.

Another object of this invention is to provide an improvedmaintained-position over-center spring interlocking mechanism forinterlocking a pair of pushbutton switches.

For a fuller understanding of the nature and objects of the invention,reference may be had to the following detailed description, taken inconnection with the accompanyin g drawings in which:

FIGURE 1 is a side view partly in elevation and partly in section, withparts broken away and with one contact block shown in phantom, of anelectric control device constructed in accordance with principles ofthis invention;

FIG. 2 is a' bottom view, with parts broken away and with one contactblock removed, of the control device shown inFlG. 1;

FIG. 3 is a side elevational view of the interlocking mechanism of FIG.1, which mechanism is shown in the other operating position;

FIG. 4 is a side view of one of the contact blocks of FIG. 1 taken fromthe side opposite that seen in FIG. 1 with the side cover of the contactblock removed for the purpose of clarity; and

FIG. 5 is a view similar to FIG. 3 of the interlocking mechanism of FIG.3 adjusted to operate with pushbuttons having a different dimension ofoperator travel.

Referring to the drawings, there is shown in FIGS. 1 and 2 an electriccontrol device 3 comprising a metallic supporting panel member 5 havingtwo pushbutton switches 7 and 9 mounted thereon. The pushbutton switches7 and 9 are of identical construction, and each comprises an operatingstructure 11 and a contact block 13. Each of the pushbutton switchescomprises a support 15 that extends outward through an opening in thepanel 5, and a clamp ring 17 that is threaded on the support 15 to drawthe support upward such that a flange 19 on the support 15 is drawnagainst a gasket 21 which is drawn against the underside of the panel 5to support the pushbutton switch on the panel 5. Each of the pushbuttonswitches comprises a pushbutton operator 25 biased to the upper positionby means of a spring 27. Each of the operators 25 comprises a shaftportion 27 that extends through an opening in the support 15 and agenerally L-shaped plate member 29 that is fixedly secured to the lowerend of the shaft 27.

As can be seen in FIG. 4, each of the contact blocks 13 comprises aninsulating housing block 31 having a cavity therein. An insulating cover33 (FIG. 2) is removed in the FIG. 4 showing. A first pair of stationarycontacts 35 are secured to conductors 37 that extend out throughopenings in the cover 33 and a second pair of stationary contacts 39 aresecured to conductors 41 that also extend out through openings in thecover 33. The conductors 37 and 41 are provided with openings thereinfor receiving connecting screws 43 (FIG. 2) that are used at theinstallation to connect conducting wires to the contact block 13. Aninsulating contact carrier 43 is supported in the cavity forrecitilinear up-and-down movement and biased to the upper position seenin FIG. 4 against the lower surface of the plate member 29 by means of aspring 45. An elongated bridging conductor 47, that is carried by thecarrier 43, is provided with four contacts 49 that are positioned at theends of the conductor 47 on opposite sides of the conductor as seen inFIG. 4. Vertical movement of the carrier 43 moves the movable contacts49 of the bridging conductor 47 into and out of engagement with thepairs of stationary contacts 35 and 39 in a well-known manner.

An over-center spring maintained-position interlocking mechanism 53(FIGS. 1-3) is supported on the pushbutton switches 7, 9 to interlockthe switches for maintained position seesaw type ope-ration. Theinterlocking mechanism 53 comprises a generally U-shaped rigid metallicsupport 55 that is secured to the supports 19 of the two pushbuttonswitches by means of a pair of screws 57. The support 55 comprises afirst pair of depending leg portions 59 and a second pair ofdependingleg portions 61. A generally U-shaped link member 63 ispivotally mounted on the leg portions 59 by means of a pin 65. Anotherlink member 67 is pivotally secured to the depending leg portions 61 bymeans of a pin 69. The support 55 also comprises an integral dependingsupport part 71. An elongated connecting arm 73 is pivotally supportedmid-way between the ends thereof on the depending part 71 by means of apin 75. As can be understood with reference to FIGS. 1 and 3, each ofthe U-shaped link members 63 and 67 is provided with three pairs ofaligned openings (in addition to the openings which receive thesupporting pins) that extend through the opposite legs thereof. A pairof spring-support pins 77 and 79 are secured to the link members 63, 67respectively in the inside openings of the link members 63, 67. Anover-center leaf spring 81 is connected at the opposite ends thereof tothe pins 77, 79 in a compressed bowed condition to connect the linkmembers 63, 67. A pair of pin mern bers 83 and 85 are secured to thelink members 63, 67 respectively in the center openings of the threepairs of aligned openings of the link members 63, 67. The elongatedconnecting arm 73 is provided with a pair of opposite slots 87 and 89 onopposite sides of the pivots 75, and the pins 83, 85 extend out throughthe legs of the link members 63, 67 (FIG. 2) into the slots 87, 89respectively to provide a lost-motion slot-and-pin type operativeconnection between the links 63, 67 and the elongated connecting arm 73.The elongated connecting arm 73 is formed with a pair of slots 91 and 93therein in proximity to the ends thereof, and a pair of pins 95 and 97,that are secured to the depending leg parts of the members 29 that areconnected to the opposite switches 7, 9, extend into these slots 91, 93to provide lost-motion slot-and-pin type connections between the members29 and the connecting arm 73.

As can be seen in FIG. 1, the operator 25 of the switch 9 is in thedepressed position wherein the bridging contact member 47 bridges thelower stationary contacts 39 (FIG. 4) of the associated contact block,and the operator 25 of the switch 7 (FIG. 1) is in the upper positionwherein the associated bridging contact member 47 bridges the uppercontacts 35 (FIG. 4) of the associated contact block 13. The pushbuttonoperators 25 of the switches 7, 9 are maintained in the position seen inFIG. 1 by means of the over-center spring maintained-positioninterlocking mechanism 53. As can be seen in FIG. 1, the spring 81biases the link member 67 in a counterclockwise direction about thepivot 69 and the spring 81 biases the link member 63 in acounterclockwise direction about the pivot 65. This force is transmittedthrough the slotand-pin connections 85, 89 and 83, 87 to bias theconnecting arm 73 in a clockwise direction about the pivot 75. Thisforce is transmitted through the connecting arm 73 by virtue of theslot-and-pin connections 93, 97 and 91, 95 to bias the member 29 of theswitch 9 to the lower position seen in FIG. 1 and to bias the member 29of the switch 7 to the upper position seen in FIG. 1. The limits ofmovement of the switches 7, 9 and the mechanism 53 are determined byengagement of the members 29 and 25 of the switches with the associatedsupport parts 15.

When it is desired to ope-rate the control device 3, the pushbuttonoperator 25 of the switch 7 is manually depressed to the lower positionthereof to move the associated bridging contact member into engagementwith the associated lower stationary contacts and to operate through theconnecting arm 73 to effect movement of the bridging contact member ofthe switch 9 to the upper position into engagement with the upperstationary contacts of the switch 9. During this movement, the pin 95 ofthe switch 7 moves in the slot 91 to rotate the connecting arm 73 in acounterclockwise direction about the pivot 75. During this movement, thelinks 63, 67 are operated by means of the slot-and-pin connections 87,83 and 85, 89 respectively such that the links are moved in clockwisedirections about their pivots 65, 69 respectively. During this movement,the pin 97 of the member 29 of the switch 9 is moved upward to move thepushbutton operator 25 of the switch 9 upward to the upper position. Asthe connecting arm 73'is pivoted from the position seen in FIG. 1 to theposition seen in FIG. 3, the connecting arm 73 moves to a horizontalposition and the link members 63, 67 move to horizontal positions duringwhich movement the spring 81 is compressed as the spring support pins77, 79 move closer to each other. When an imaginary line drawn throughthe centers of the pins 65, 83, 77, 75, 79, 85, 69 is horizontal, theparts are on dead center, and additional movement will move the partsover center whereupon the spring 81 will operate with a snap action tomove the link members 63, 67 clockwise about their respective pivots 65,69 to the position seen in FIG. 3. During this movement, the links 63,67 operate through the slot-in-pin connections 87, 83 and 89, 95respectively to move the connecting arm 73 to the position seen in FIG.3, which movement of the connecting arm 73 operates through theslot-and-pin connections 91, 95 and 93, 97 respectively to move themembers 29 to the position seen in FIG. 3. Movement of the parts islimited in the mainner that was described with reference to FIG. 1. Thespring member 81 operates to bias the parts of the position seen in FIG.3 to thereby provide that the pushbutton switches will be maintained inposition until a subsequent manual operation which operation would beeffected by depressing the pushbutton operator 25 of the switch 9. Itcan be understood that the spring 81 serves to provide a positive actionduring each operation of the control device 3 and to maintain thecontrol device 3 in position after each manual opera tion until asubsequent manual operation. As can be understood with reference toFIGS. 1 and 3, the mechanism 53 ties the pushbutton switches 7, 9together for seesaw type maintained-position operation in the mannerhereinbefore described.

The maintained-position interlocking mechanism 53 described withreference to FIGS. 1-4 is constructed to provide effective over-centeroperation to the over-center operating positions seen in FIGS. 1 and 3under the control of the two pushbutton switches 7 and 9 that areconstructed with a certain dimension (for example inch) of travel of thepushbutton operators 25 (FIG. 1) and contact carriers 43 (FIG. 4). Theinterlocking mechanism 53 can be adjusted to provide over-centermaintamed-position interlocking between two pushbutton switches having alesser dimension (for example of an inch) of travel of the operators 25and contact carriers 43. The adjusted interlocking mechanism is shown inFIG. 5. For the purpose of clarity, only two reference characters areutilized in FIG. 5 to highlight the adjusted condition of theinterlocking mechanism. The interlocking mechanism of FIG. 5 is exactlylike that of FIGS. 1-3 except that the pins 83 and 85 that connect thelink members 63 and 67 respectively to the connecting arm 73 have beenmoved from the center holes in which they appear in FIG. 3 to the holesthat are positioned between the pivots of the link members and thecenter holes. The lengths of the lever arms of the link members 63 and67 have therefore been reduced from the lengths shown in FIG. 3, whereinthe length extends from the pivots 65, 69 to the pins 83, 85respectively that are positioned in the center holes of the three holesshown in each of the links in FIG. 3, to the lesser lengths seen in FIG.5 wherein the lengths extend from the pivots 65, 69 to the pins 83, 85respectively that are positioned in the openings that are closest to thepivots of the link members 63, 67. Thus, the over-center spring memberwill be operated between the two maintained over-center operatingpositions under the control of pushbutton operators that have a lesserdimension of operator travel than that described with reference to FIGS.1-3. The interlocking mechanism FIG. 5 will interlock a pair ofpushbutton switches in the same manner as that described with referenceto FIGS. \14. Interlocking mechanisms constructed in accordance withthis invention have been successfully tested on pushbutton switcheshaving a dimension operator travel of of an inch (constructed inaccordance with the embodiment of FIGS. 1-3) and also with pushbuttonswitches having a dimension of operator travel of of an inch(constructed in accordance with the embodiment of FIG. 5). It can beunderstood that an interlocking mechanism could be constructed with aplurality of openings therein for a plurality of different adjustedover-center maintained-positions and that the mechanism could beutilized with different pushbutton switches having a plurality ofdifferent dimensions of operator travel by merely changing the positionof the pin that is mounted on the link members and that extends intoslots in the connecting arm to operatively connect the link members withthe connecting arm.

Having described the invention in accordance with the patent statutes,it is to be understood that various changes and modifications may bemade in the structural details and arrangement of parts withoutdeparting from some of the essential features of the invention.

I claim as my invention:

1. A maintained-position mechanism for interlocking a pair of pushbuttonswitches, said mechanism comprising support means, an elongatedconnecting arm pivotally mounted intermediate the ends thereof on saidsupport means, a pair of link members, means pivotally mounting saidlink members on said support means on opposite sides of the pivot ofsaid connecting arm, means connecting said connecting arm with said linkmembers, over-center spring means connecting said link members, saidconnecting arm being reciprocally pivotal between two positions, uponeach operation of said connecting arm between said two positions saidconnecting arm driving said link members to operate said over-centerspring means over-center, and said over-center spring means in each ofthe two overcenter positions operating to maintain said connecting armin position until a subsequent operation of said connecting arm.

2. A maintained-position mechanism according to 1, and means forconnecting said connecting arm to a pair of pushbutt-on operators onopposite sides of the pivot of said connecting arm.

3. A maintained-position mechanism according to claim 2, and said meansconnecting said connecting arm with said link members comprising aseparate slot-and-pin type connection between each of said link membersand said connecting arm.

4. A maintained-position mechanism according to claim 2, and saidover-center spring means comprising a flat leaf spring connected in abowed position between said link members.

5. A maintained-position mechanism according to claim 4, and said meansconnecting said connecting arm with said link members comprising aseparate slot-and-pin type connection between each of said link membersand said connecting arm.

6. A maintained-position mechanism according to claim 3, and each ofsaid separate slot-and-pin type connections between each of said linkmembers and said connecting arm being adjustable to vary the length ofthe lever arm of each link member between the pivot of the link memberand the associated slot-and-pin type connection.

7. A maintained-position mechanism according to claim 1, said supportcomprising a generally U-shaped support member comprising a first pairof spaced leg supports and a second pair of spaced leg supports, each ofsaid link members comprising a generally U-shaped member, a first ofsaid link members being pivotally supported between said first pair ofspaced leg supports and the second of said link members being pivotallysupported between said second pair of spaced leg supports, said linkmembers extending from the pivots thereof toward each other, each ofsaid link members comprising a spring supporting pin supported betweenthe associated legs in proximity to the free end of the link member,said over-center spring means being connected between said springsupporting pins, each of said link members comprising a connecting pinpositioned between the pivot thereof and the associated springsupporting pin, said elongated connecting arm having a pair of slotstherein on opposite sides of the pivot thereof, and said connecting pinsof said link members being positioned in said slots to provide aseparate lost-motion slot-and-pin type connection between each of saidlink members and said connecting arm.

8. A maintained-position mechanism according to claim 7, and means forrepositioning the connecting pin on each of said link members to varythe lever arm of each link member which lever arm extends from the pivotof the link member to the slot-and-pin connection of the link memberwith the connecting arm.

9. A maintained-position mechanism according to claim 7, and saidover-center spring means comprising a leaf spring supported between saidlink members on said spring supporting pins in a bowed condition.

10. A maintained-position mechanism according to claim 9, and saidconnecting arm having a pair of slots therein at opposite ends thereoffor receiving a pair of pin members of a pair of push-button operatorsto thereby provide for over-center maintained-position seesaw typeoperation of said pushbutton operators.

References Cited UNITED STATES PATENTS 2,487,970 11/ 1949 Horn et a1.2,519,899 8/1950 Gaynor. 2,713,092 7/ 1955 Rucks'et al ZOO-5 3,303,2952/ 1967 Davis 200-5 ROBERT K. SCI-IAEFER, Primary Examiner.

I. R. SCOTT, Assistant Examiner.

